1. Technical Field
The invention relates to forming components for use in containers such as the container body and/or the end shell for use as a closure end for the container body from a blank of metal in a press. More particularly, the invention relates to a method and apparatus in which the operations are formed at three distinct levels in the press, and in which the press has a fixed stock plate to provide for higher speeds to increase the output production of the press.
2. Background Information
It is well known in the container forming art to form two piece containers, that is, containers in which the container bodies are one-piece members and the end closure or shell is a separate piece. These component pieces are formed by initially stamping disk-shaped blanks from a strip of sheet metal material and then subsequently drawing the blank into a cylindrical cup-shaped member and then profiling the bottom wall. The can body or shell is then ejected from the press for subsequent forming and/or end curling at a separate station. Speed of press operation and the number of first stage can bodies and/or end shells is critical with higher production speed being of critical importance.
One of the factors which limits the speed of the press is the scrap web or matrix which results when a plurality of the blanks are cut from the strip of sheet metal at each press stroke. This scrap web limits the speed of the press since the stock plate on which it initially rests is resiliently mounted and moves downwardly during each of the blanking operations and then returns to the input level before the sheet material moves linearly for the next press stroke. Another factor which effects the speed of operation is the profiling of the bottom wall of the cup-shaped member whether it be a container body or an end shell.
The closest prior art to the subject invention is believed shown in U.S. Pat. Nos. 4,903,521; 4,977,772 and 5,881,593. These three patents show the formation of container components including the container body and the end shells, in a high speed press wherein the formed blank is passed through the blank and draw die to a lower level for profiling of the bottom wall, afterwhich it is ejected from the press at or near the profiling level. However, these presses all have a resiliently mounted stock plate which is depressed when cutting the disk-shaped blank from the sheet material requiring return of the scrap web and connected sheet material back to the beginning level prior to the sheet material being moved linearly into the press for the next press cycle or ram stroke. Although this reciprocal movement of the web and sheet material takes a very short period of time, it becomes critical when the speed of these presses is generally within the range of between 300 and 700 strokes per minute. Thus, the saving of a fraction of a second during each press stroke amounts to a considerable increase in production over an extended period of time.
Likewise, the scrap web being continually moved upwardly and downwardly during each stroke as the strip material moves through the press occasionally will cause press jamming requiring stopping of the press and removal of the scrap material therefrom.
Therefore, the need exists for a modified press and unique tooling therefore which increases production by eliminating reciprocal movement of the sheet material and scrap web during each stroke and which improves the speed of profiling the bottom of the preformed container component.
Objectives of the invention include providing an improved apparatus and method for forming container components, such as the cup-shaped container bodies and/or the end shells therefore, preferably in a double action press from sheet metal material wherein the material is blanked at a first level, drawn into a generally cylindrical cup-shaped blank at a second level by a blank and draw die, and then moved through the die by the continued single stroke of the press to a third level whereat the bottom of the cup-shaped blank is profiled, afterwhich it is ejected from the press at the third level.
Another feature of the invention is to provide such an improved press and method in which the sheet material is fed into the press at a first level on a fixed stock plate where it is blanked into one or a plurality of disk blanks, which disk blanks are clamped against the top surface of the blank and draw die at a second level, where they are drawn into the shallow cup-shaped configuration by the continued downward stroke of the draw pad.
A further objective of the invention is to provide such a method and apparatus in which the bottom profile pad is cam actuated and moves upwardly into engagement with the bottom panel of the cup-shaped blank for profiling the cup at the third level into a can body or end shell, afterwhich the profile pad is withdrawn and the container component ejected from the press at the third level by pressurized air.
A further objective of the invention is to fixedly mount the bottom profile pad at the third level surrounded by a movable knockout ring, which moves the bottom profiled cup-shaped blank to the third level for subsequent discharge from the press after profiling the bottom wall of the previously formed shallow cup.
These features and objectives of the invention are obtained by the improved method of forming a container component from a strip of metal material fed into the press, the general nature of which may be stated as including the steps of providing the press with a fixed stock plate; feeding the strip material onto the fixed stock plate of the press at a first level; cutting a blank from the strip material at said first level; clamping the blank against a blank and draw die at a second level; forming a shallow cup from the blank by advancing a punch assembly beyond the second level toward a third level; profiling a bottom wall of the cup adjacent a third level to form the container component by continuing to advance the punch assembly through the die to the third level; and removing the container component from the press at the third level.
The objectives of the invention are further obtained by the improved apparatus of the present invention, the general nature of which may be stated as including a base; a stock plate immovably mounted on the base and defining a first level; a cut edge carried by the base at said first level; a reciprocally mounted blank and draw die having a top clamping surface defining a second level mounted on the base; a discharge opening defining a third level below the clamping surface of the die; a profile pad mounted on the base having a top profile surface generally adjacent with the third level; a draw pad ring reciprocally mounted for clamping the blank disk against the clamping surface of the die; a draw punch reciprocally movably mounted within the draw pad ring for moving the blank disk through the die to form a shallow cup-shaped blank and into forming engagement with the profile pad to form the container component in a single stroke.